CIS tax deduction calculator This calculator helps calculate any necessary CIS Tax Deductions. Labour Charge (£): The cost of all labour charged (net of travel and subsistence and any VAT charged by the sub contractor). Materials Charge (£): The cost of all materials supplied (Include VAT if the sub contractor is not VAT registered). Payment under deduction: Yes No Gross Is the subcontractor verified with HMRC for payment under deduction? Calculate Note: These calculations are only for illustrative purposes and are not a substitute for professional advice.